Conventional reactors used in chemical experiments comprise a metallic tube made of, e.g., stainless steel, and franges or cap nuts provided to both ends of the metallic tube by means of screws or by welding so that a given catalyst can be introduced into or withdrawn from the metallic tube, and a feed inlet and a product outlet are provided thereto (see FIGS. 3 and 4).
In chemical experiments, it is necessary for the catalyst to be exchanged for each experiment. For this reason, the reactor should be disassembled or its upper and lower parts should be dismantled for each experiment. Moreover, when a short reaction tube is used, a fixing portion of a wrench cannot be provided in the vicinity of the frange in view of the necessity of heat insulation and, therefore, it is necessary for nuts to be fitted to or removed from the upper and lower parts of the reactor. This will give rise to various problems; for example, frange nuts fracture when they are fitted and removed several times and the reaction tube is twisted. Thus no suitable reactor for chemical experiments has been available.